Gear detection circuit and wrist watch

ABSTRACT

A gear position detection device for detecting a gear having multiple fingers is provided. The detection device includes a substrate, a control chip, and a drive line, a sense line, a first drive electrode, a second drive electrode, a first sense electrode and a second sense electrode formed on the substrate. The first and second drive electrodes are connected to the drive line to receive a drive signal. The first and second sense electrodes form induced electric field respectively with the first and second drive electrodes, and respectively output a first detected signal and a second detected signal via the sense line. The control chip outputs the drive signal via the drive line, receives the first and second detected signals via the sense line, calculate a differential signal between the first and second detected signals, and count a number of high levels of the differential signal to count a finger number.

RELATED APPLICATIONS

The present application is a continuation application of U.S.application Ser. No. 15/805,688, filed on Nov. 7, 2017 the disclosure ofwhich is hereby incorporated by reference herein in its entirety.

BACKGROUND 1. Field of the Disclosure

This disclosure generally relates to gear position detection, moreparticularly, to a capacitive gear position detection device and a wristwatch using the same that identify a gear position and a rotatingdirection of a gear by detecting a number of binary one and phases ofdetected signals outputted by a capacitive detector.

2. Description of the Related Art

The gear used in a wrist watch generally has the requirement of highoperating accuracy and a small size. To detect the gear position orrotation angle, the detection device should be small enough to bearranged inside of the wrist watch. Meanwhile, the power consumptionduring the detection should be as small as possible.

It is known that an optical detection device can be used to detect thegear position or rotation angle. However, the problem of using theoptical detection device is that the light beam can repeatedly reflectedin an interval space of the watch to cause interference. In order toachieve high detection accuracy, the interference caused by thereflected light has to be obviated but the cost can be increasedaccordingly. In addition, a light source and consume relatively highpower when emitting light.

Generally, a user can adjust hands of a watch manually to change thetime being indicated by the hands. However, in some particularapplications such as the satellite watch or GPS watch whose hour andminute hands can be automatically calibrated, e.g., at a specific timeof a day, to maintain a correct time according to a standard time fromoutside. Accordingly, the user does not need to adjust time byhim/herself. However, due to some specific reasons, such as the watchbeing damaged or a defective item, that cause gears in the wrist watchto have an offset, an automatically calibrated time can have a timeshift from the standard time. Although the user can manually correct thedeviated time to the correct time, the wrist watch still automaticallycalibrates itself to the deviated time such that the user has to correctthe deviated time manually each time after the automatic calibration isperformed.

Accordingly, the present disclosure provides a capacitive gear positiondetection device that has the advantages of small size and low powerconsumption as well as capable of detecting the deviated finger numberand help to recover to the correct time correspondingly.

SUMMARY

The present disclosure provides a capacitive gear position detectiondevice that is arranged only at a single side of a gear to occupy asmaller space.

The present disclosure further provides a capacitive gear positiondetection device and a wrist watch that have an index position toconfirm a rotation angle of a gear.

The present disclosure further provides a capacitive gear positiondetection device and a wrist watch that have multiple sets of capacitivesensors to confirm a rotation direction of gear and increase theidentification resolution.

The present disclosure further provides an operating method of a wristwatch that confirms the correctness of an automatic calibrated time, andthe automatic calibrated time is re-adjusted to a correct time when theautomatic calibrated time is detected not being correct.

The present disclosure provides a wrist watch including a substrate, agear, and a first drive electrode, a second drive electrode, a firstsense electrode and a second sense electrode formed on the substrate.The gear has a plurality of fingers and is rotatable with respect to thesubstrate. The first sense electrode is arranged adjacent to the firstdrive electrode, and the second sense electrode is arranged adjacent tothe second drive electrode. The first drive electrode and the firstsense electrode form a first electrode set, the second drive electrodeand the second sense electrode form a second electrode set, and thefirst electrode set and the second electrode set are arranged in anarrangement that when one of the first and second electrode sets arerotated to totally face one of the plurality of fingers, the other oneof the first and second electrode sets is between two fingers of theplurality of fingers.

The present disclosure further provides a detection circuit configuredto detect rotation of a gear having a plurality of fingers. Thedetection circuit includes a substrate, a control chip, and multipledrive lines, multiple sense lines, a first drive electrode, a seconddrive electrode, a first sense electrode and a second sense electrodeformed on the substrate. The substrate is configured to be arrangedopposite to the gear. The first drive electrode and the second driveelectrode are respectively connected to one of the multiple drive lines.The first sense electrode and the second sense electrode arerespectively connected to one of the multiple sense lines, wherein thefirst sense electrode is arranged adjacent to the first drive electrode,and the second sense electrode is arranged adjacent to the second driveelectrode. The control chip is connected to the first and second driveelectrodes via the one of the multiple drive lines, and connected to thefirst and second sense electrodes via the one of the multiple senselines.

The gear position detection device of the present disclosure is arrangedcorresponding to any one gear of multiple gears in a wrist watch, andthe positions of other gears engaged with the detected gear areobtainable as well.

In the gear position detection device of the present disclosure, theshape and size of the detecting electrode set are arranged correspondingto the shape and size of the detected gear. Preferably, a size of eachdetecting electrode set is smaller than the size of fingers and a spacebetween adjacent fingers to effectively use the fingers to shield thecapacitive induction so as to generate distinguishable detected signals.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects, advantages, and novel features of the present disclosurewill become more apparent from the following detailed description whentaken in conjunction with the accompanying drawings.

FIG. 1 is a schematic diagram of a wrist watch according to oneembodiment of the present disclosure.

FIG. 2 is a block diagram of a gear position detection device accordingto one embodiment of the present disclosure.

FIG. 3 is an operational schematic diagram of a gear position detectiondevice according to one embodiment of the present disclosure.

FIG. 4 is a schematic diagram of a gear position detection deviceaccording to one embodiment of the present disclosure.

FIG. 5 is a schematic diagram of detected signals of a gear positiondetection device according to one embodiment of the present disclosure.

FIG. 6 is another schematic diagram of detected signals of a gearposition detection device according to one embodiment of the presentdisclosure.

FIG. 7 is a flow chart of an operating method of a wrist watch accordingto one embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENT

It should be noted that, wherever possible, the same reference numberswill be used throughout the drawings to refer to the same or like parts.

Referring to FIG. 1, it is a schematic diagram of a wrist watch 9according to one embodiment of the present disclosure. The wrist watch 9includes a gear 10 and a gear position detection device 3. The gear 10includes a plurality of fingers 101 separately formed at an edge of thegear 10. It is appreciated that a number, a shape and a size of theplurality of fingers 101 shown in FIG. 1 are not to limit the presentdisclosure. It should be mentioned that although FIG. 1 shows that thegear 10 has an axle hole at the center, it is not to limit the presentdisclosure. In other embodiments, the gear 10 does not have any axlehole. In the present disclosure, the gear 10 is preferably made ofmetal.

The gear position detection device 3 includes a substrate 31, a controlchip 33 and a detection circuit (including traces and electrodes) formedon the substrate. It is appreciated that although FIG. 1 shows a singlegear 10, the gear 10 is one of multiple gears in the wrist watch 9. Morespecifically, the gear position detection device 3 of the presentdisclosure is arranged opposite to single side of one (generallyselecting the one which is easier to be detected) of multiple gears inthe wrist watch 9 to effectively reduce the occupied space. As themultiple gears engage with each other, if the correct position (orrotation angle) of the detected single gear is confirmed, positions (orrotation angles) of other multiple gears are ensured at the same time.

Referring to FIG. 2, it is a block diagram of a gear position detectiondevice 3 according to one embodiment of the present disclosure. Inaddition to the plurality of fingers 101, the gear 10 further includes asingle index through hole IH as a reference position (illustrated withan example below). It should be mentioned that although FIGS. 1 and 2show that the index through hole IH is aligned with one of the pluralityof fingers 101 along a radial direction of the gear 10, it is not tolimit the present disclosure. In other embodiments, the index throughhole IH is aligned with a space between two adjacent fingers of theplurality of fingers 101 along a radial direction of the gear 10.

The gear position detection device 3 includes a drive line TX and senselines RX formed on the substrate 31, wherein the substrate 31 is aprinted circuit board (PCB) or a flexible circuit board (FCB). Thecontrol chip 33 is used to output a drive signal SD via the drive lineTX, and receive detected signals SR1 and SR2, referring to FIG. 4 forexample, via the sense lines RX. It is appreciated that the trace layoutof the drive line TX and the sense line RX shown in FIGS. 1 to 4 is onlyto illustrate, but not to limit the present disclosure.

The gear position detection device 3 includes a first drive electrodeDE1, a second drive electrode DE2, a first sense electrode DE2, a secondsense electrode RE2 formed on the substrate 31. The first driveelectrode DE1 and the second drive electrode DE2 are connected to thedrive line TX to receive the drive signal SD. The first sense electrodeRE1 and the second sense electrode RE2 are used to respectively forminduced electric field, e.g., E1 and E2 shown in FIG. 3, with the firstdrive electrode DE1 and the second drive electrode DE2, and respectivelyoutput a first detected signal SR1 and a second detected signal SR2 viathe sense lines RX.

In the present disclosure, the first drive electrode DE1 and the firstsense electrode RE1 are considered as a first electrode set, and thesecond drive electrode DE2 and the second sense electrode RE2 areconsidered as a second electrode set. The first electrode set and thesecond electrode set are arranged in an arrangement that when one of thetwo electrode sets (FIGS. 1 to 4 showing the second electrode set)totally opposites to one of the plurality of fingers 101 (or fullysheltered by one finger), the other one of the two electrode sets (FIGS.1 to 4 showing the first electrode set) is between two adjacent fingersof the plurality of fingers 101 (or fully exposed from the fingers). Inother words, the first electrode set and the second electrode set areseparated by a half finger pitch (e.g., one finger pitch being adistance between central lines of two adjacent fingers) along thecircumferential direction.

Referring to FIG. 3, it is an operational schematic diagram of a gearposition detection device 3 according to one embodiment of the presentdisclosure. Based on the above arrangement of the first electrode setand the second electrode set, when one of the multiple fingers 101totally covers the second electrode set, due to the blocking effect ofthe finger 101, the electric field E2 between the second drive electrodeDE2 and the second sense electrode RE2 is suppressed such that a valueof the second detected signal SR2 has a minimum value. As shown in FIG.3, as the first electrode set is totally not covered by any finger 101,the electric field E1 between the first drive electrode DE1 and thefirst sense electrode RE1 is not suppressed at all such that a value ofthe first detected signal SR1 has a maximum value. When one electrodeset is between states of fully covered and fully exposed, an intensityof the electric field is between intensity of the electric field E1 andintensity of the electric field E2.

In some embodiments, the gear position detection device 3 furtherincludes a third drive electrode DE3, a fourth drive electrode DE4, athird sense electrode RE3 and a fourth sense electrode RE4 formed on thesubstrate 31. The third drive electrode DE3 and the fourth driveelectrode DE4 are connected to the drive line TX to receive the drivesignal SD, wherein the drive signal SD is preferably a square wave, butis selectable from other periodic signals. The third sense electrode RE3and the fourth sense electrode RE4 are used to form induced electricfield (similar to the electric fields E1 and E2 shown in FIG. 3)respectively with the third drive electrode DE3 and the fourth driveelectrode DE4, and respectively output a third detected signal and afourth detected signal via the sense line RX.

The third drive electrode DE3 and the third sense electrode RE3 areconsidered as a third electrode set, and the fourth drive electrode DE4and the fourth sense electrode RE4 are considered as a fourth electrodeset. The third electrode set and the fourth electrode set are arrangedin an arrangement that when the first electrode set or the secondelectrode set (FIGS. 1 to 4 showing the second electrode set) fullyfaces one of a plurality of fingers 101 (fully covered), the thirdelectrode set and the fourth electrode set do not fully face any one ofthe plurality of fingers 101 and do not totally between two adjacentfingers of the plurality of fingers 101, i.e. partially covered.

Referring to FIG. 4, it is another schematic diagram of a gear positiondetection device 3 according to one embodiment of the presentdisclosure. If it is assumed that a distance d1 between the firstelectrode set and the second electrode set is a half finger pitch, adistance d2 between the third electrode set and the second electrode setis ¾ finger pitch, and a distance between the third electrode set andthe fourth electrode set is also d1.

Referring to FIG. 5, it is a schematic diagram of detected signals of agear position detection device 3 according to one embodiment of thepresent disclosure. Based on the above arrangement of the firstelectrode set, the second electrode set, the third electrode set, andthe fourth electrode set, the third detected signal has the samewaveform (assuming the third electrode set and the first electrode sethaving an identical area and shape) as the first detected signal SR1 buthas a phase shift therefrom, and the fourth detected signal has the samewaveform (assuming the fourth electrode set and the second electrode sethaving an identical area and shape) as the second detected signal SR2but has a phase shift therefrom.

In FIG. 4, assuming that the first electrode set is a channel A, thesecond electrode set is a channel A′, the third electrode set is achannel B, and the fourth electrode set is a channel B′. In FIG. 4-5,detected signals of the channel A and channel A′ are respectively shownby SR1 and SR2 (with 180 degrees phase difference). Detected signals ofthe channel B and channel B′ are also respectively indicated by SR1 andSR2 but with a phase shift. FIG. 4 further shows a channel I and achannel I′ which are index electrode sets (described below).

In this embodiment, the channels B and B′ are used to identify arotation direction of the gear 10. However, when the gear positiondetection device 3 is applied to a device that does not need to detectthe rotation direction of the gear 10, the channels B and B′ are notimplemented.

The gear position detection device 3 of the present disclosure furtherincludes an index electrode set (e.g., channel I) that has an indexdrive electrode IDE, which is connected to the drive line TX and used toreceive the drive signal SD, and an index sense electrode IRE, which isconnected to a sense line RX and used to output an index detected signalS_(ID), wherein said index detected signal S_(ID) is used as a referencefor triggering or stopping counting the fingers 101. In one embodiment,the index electrode set is aligned with the first electrode set or thesecond electrode set. As the first electrode set and the secondelectrode set are used to detect fingers 101 of the gear 10 and the gear10 has a circular shape, the first electrode set and the secondelectrode set are arranged parallel along a circular curve correspondingto an edge of the gear 10, and the index drive electrode IDE and theindex sense electrode IRE are aligned with the first electrode set orthe second electrode set along a direction perpendicular to saidcircular curve. If the gear 10 is considered, the index drive electrodeIDE and the index sense electrode IRE are aligned with the firstelectrode set or the second electrode set (FIGS. 1 to 4 showing beingaligned with the second electrode set) along a radial direction of thegear 10 such that when the control chip 33 detects the index detectedsignal S_(ID), one of the first electrode set and the second electrodeset is just covered by one of multiple fingers 101.

In the present disclosure, the shape and size of the index electrode setdo not necessary to be identical to those of the first electrode set andthe second electrode set; whereas the first and second electrode setspreferably have an identical shape and size.

Referring to FIGS. 2 and 4-6, the control chip 33 includes, for example,a drive circuit 331 used to output the drive signal SD to the drive lineTX, wherein the drive circuit 331 is, for example, a signal generatorwhich is used to generate a periodic signal. The control chip 33includes, for example, at least one analog-to-digital converter (ADC)333 used to convert the detected signal (e.g., a first detected signalSR1 and a second detected signal SR2 shown in FIG. 5) received from thesense lines RX to digital signals. The control chip 33 further includes,for example, a digital signal processor (DSP) 335 used to receive thedigital signals and calculate a differential signal S_(diff) between thedigitized first detected signal SR1 and the digitized second detectedsignal SR2 as shown in FIG. 5. In this way, the control chip 33 counts(e.g., further including a counter) a number of high levels (e.g.,binary one) of the differential signal S_(diff) as a method for countinga number of fingers 101 passing the first electrode set and the secondelectrode set in rotation.

FIG. 5 shows on example in which when a phase of the digitized firstdetected signal SR1 leads that of the digitized second detected signalSR2 (e.g., within time intervals t1), a binary one (i.e. high level) isobtained; whereas when a phase of the digitized first detected signalSR1 lags that of the digitized second detected signal SR2 (e.g., withintime intervals t2), a binary zero (i.e. low level) is obtained.

It should be mentioned that although the above illustrations take anexample of firstly digitizing the detected signals and then performingthe differential operation, the present disclosure is not limitedthereto. In other embodiments, the control chip 33 includes, forexample, an analog differential circuit used to performing thedifferential operation between the first detected signal SR1 and thesecond detected signal SR2 at first, and then the ADC 333 converts thedifferential signal S_(diff) to a digital signal. Therefore, thedifferential signal S_(diff) is a digital signal or an analog signaldepends on the circuit architecture of the control chip 33.

As mentioned above, in some embodiments the gear position detectiondevice 3 further includes a third electrode set used to generate a thirddetected signal and a fourth electrode set used to generate a fourthdetected signal. As mentioned above, the waveform of the third detectedsignal is substantially identical to that of the first detected signalSR1 but with a phase shift; whereas the waveform of the fourth detectedsignal is substantially identical to that of the second detected signalSR2 but with a phase shift. The control chip 33 also calculates adifferential signal S_(diff) between the third detected signal and thefourth detected signal. For illustration purposes, herein thedifferential signal between the first and second detected signals isreferred to S_(diff1), and the differential signal between the third andfourth detected signals is referred to S_(diff2). As shown in FIG. 6,the second differential signal S_(diff2) has a phase shift from thefirst differential signal S_(diff1), wherein the amount of the phaseshift is determined according to a distance d2 (as shown in FIG. 4)between the third electrode set and the second electrode set.

The control chip 33 further identifies a rotation direction of the gear10 according to phases of the first differential signal S_(diff1) andthe second differential signal S_(diff2) after the index detected signalS_(ID) is detected. For example in the embodiment of FIGS. 1-4 and 6,after the index detected signal S_(ID) appears and when detecting arising edge Rcc1 of the first differential signal S_(diff1) at first andthen detecting a rising edge Rcc2 of the second differential signalS_(diff2), the control chip 33 identifies the clockwise rotation (e.g.,signals S_(diff1) and S_(diff2) moving from right to left in FIG. 6); onthe contrary, after the index detected signal S_(ID) appears and whendetecting a rising edge Rc2 of the second differential signal S_(diff2)at first and then detecting a rising edge Rc1 of the first differentialsignal S_(diff1), the control chip 33 identifies the counterclockwiserotation (e.g., signals S_(diff1) and S_(diff2) moving from left toright in FIG. 6). In other embodiments, the control chip 33 detectsfalling edges of the first differential signal S_(diff1) and the seconddifferential signal S_(diff2) depending on the architecture of thecontrol chip 33.

In addition, by arranging the third electrode set and the fourthelectrode set as FIGS. 1-4, the detecting resolution of the fingers 101is improved to ½ finger pitch.

In addition, as FIGS. 1-4 show that the index drive electrode IDE andthe index sense electrode IRE are aligned with the second electrode set,FIG. 6 shows that a phase of the index detected signal S_(ID)corresponds to that of the first differential signal S_(diff1). In otherembodiments, when the index drive electrode IDE and the index senseelectrode IRE are aligned with the fourth electrode set, the phase ofthe index detected signal S_(ID) corresponds to that of the seconddifferential signal S_(diff2). In the present disclosure, when thecontrol chip 33 receives the index detected signal S_(ID), the countingof the number of the fingers 101 is started or stopped, i.e. thedetected index detected signal S_(ID) is used as a reference forcounting.

In some embodiments, to form the index detected signal S_(ID) as asquare wave for the comparison, the control chip 3 further compares theindex detected signal S_(ID) with a threshold TH. When an amplitude ofthe index detected signal S_(ID) is higher than the threshold TH, a highvoltage level is given, and when an amplitude of the index detectedsignal S_(ID) is lower than the threshold TH, a low voltage level isgiven. By appropriately selecting a value of the threshold TH, a highlevel interval of the index detected signal S_(ID) is substantiallyidentical to a high level interval of the differential signal S_(diff).In addition, a size of the index through hole IH is properly arranged,and by selecting the threshold TH, an interval of the index detectedsignal S_(ID) higher than the threshold TH is substantially identical tothe high level interval of the differential signal S_(diff).

In other embodiments, the index drive electrode IDE and the index senseelectrode IRD are not exactly aligned with other electrode sets but witha shift therefrom. In this case, the differential signal in FIG. 6(e.g., the first differential signal S_(diff1)) has a phase shift fromthe index detected signal S_(ID). The control chip 33 includes, forexample, a memory used to store information of this phase shift.Accordingly, when receiving the index detected signal S_(ID), thecontrol chip 33 subtracts this phase shift therefrom or adds this phaseshift thereto to start to count or stop counting the number of thefingers 101.

The gear position detection device 3 of the present disclosure isfurther used to, for example, adjust a time deviation of a wrist watch9, e.g., adjusting an auto calibrated time of a satellite watch or a GPSwatch. Said auto calibrated time (e.g., a standard time) is not correctdue to some reasons, e.g., the engagement of multiple gears being wrong.

Please referring to FIG. 7, it is a flow chart of an operating method ofa wrist watch according to one embodiment of the present disclosure,which includes the steps of: confirming a gear position (Step S71);storing information of a current position of the gear (Step S72);rotating the gear (Step S73); counting a number of fingers (Step S74);identifying whether an index position is reached (Step S75); if not,continuously rotating the gear; if yes, comparing the counted number ofthe fingers with the information of the current position (Step S76);identifying whether the two are matched (Step S77); if not, adjusting aposition of the gear (Step S78); if yes, ending the operation (StepS79).

Step S71: For example, the wrist watch 9 has an antenna for receiving astandard time signal, and the control chip 33 automatically controls thegear 10 (e.g., using a micromotor) to a current position representingthe standard time, wherein the standard time signal is a satellitesignal or a time zone signal associated with a GPS location. Thestandard time signal is considered as indicating a correct time, and thecontrol chip 33 controls, for example using a micromotor, hands of thewrist watch 9 to said correct time.

Step S72: When the gear 10 is rotated to the current position to allowthe wrist watch 9 to represent the calibrated time (e.g., the standardtime), the control chip 33 stores information corresponding to thecurrent position of the gear 10. For example, the memory 337 includes anonvolatile memory used to store information of current positions of thegear 10 corresponding to every moment, wherein the information of thecurrent position includes, for example, a finger number to be countedfrom the current position till the control chip 33 detecting the indexdetected signal S_(ID) (i.e. to the position of the index through holeIH). In another embodiment, when said calibrated time is always the samemoment of a day, the memory 337 only stores information of the currentposition of the gear 10 corresponding to the single moment of a day.

Step S73: Then the gear 10 rotates according to the normal operation ofthe wrist watch 9, and the control chip 33 does not need to rotate thegear 10 using a particular speed. That is, the normal operation hereinis referred to that multiple gears (including the gear 10) rotatesimultaneously to allow the wrist watch 9 to indicate time normally.

Step S74: When the gear 10 starts to rotate, the control chip 33 startsto count a number of high levels of the differential signal S_(diff1),e.g., the numbers 1, 2, 3 . . . shown in FIG. 6. Each count (e.g., asquare wave shown in FIG. 6) indicates that one finger 101 passes thedetected electrode set, and the control chip 33 stores the countednumber of the fingers 101 in the memory 337.

Step S75: When the control chip 33 detects the index detected signalS_(ID), the counting is stopped and the Step S76 is entered. After theStep S76 is entered, the count number is reset to zero. If the indexdetected signal S_(ID) is not detected, the number of the fingers 101 iscounted continuously (i.e. repeating the Steps S73-S75).

Step S76: The control chip 33 then compares the counted number of thefingers 101 and the information of the current position of the gear 10(already stored in the memory 337 in the Step S72).

Step S77: When the counted number of the fingers 101 matches theinformation of the current position, it means that the auto calibratedtime is correct and no further adjustment is required. The Step S79 isthen entered and the operation is ended.

Step S78: When the counted number of the fingers 101 does not match theinformation of the current position, it means that the auto calibratedtime is wrong. The control chip 33 rotates the gear 10 by a differencenumber between the counted number of the fingers 101 and the storedfinger number, e.g., using a micromotor to rotate the gear clockwise orcounterclockwise by at least one finger to allow the wrist watch 9 toindicate the correct time.

More specifically, as the embodiment of the present disclosure has theindex sense electrode IRE used to output the index detected signalS_(ID), the index detected signal S_(ID) is detected one time when thegear 10 rotates 360 degrees. Therefore, the index detected signal S_(ID)is used as a reference of the gear position (or angle). When the countedgear number does not match an expected number, it is known that the gearposition is wrong. In addition to detecting the wrong position, thepresent disclosure further adjusts the position or rotation angle of thegear 10 (by adjusting the difference number) to allow the gear positionto recover to the correct position. Accordingly, the gear positiondetection device 3 of the present disclosure has the functions of botherror detection and error cancellation.

In addition, FIG. 4 shows another index electrode set (channel I′) whichis used to confirm the differential signal between the third and fourthelectrode sets, and the operating method and function thereof areidentical to the channel I as shown in FIG. 6, and thus details thereofare not repeated herein. As the position detection function of the gearposition detection device 3 is implementable by only using the channelI, the channel I′ is not necessary to be implemented. If the channel I′is implemented, the second differential signal S_(diff2) betweenchannels B and B′ is directly confirmed without using a phase differencebetween the two differential signals S_(diff1) and S_(diff2) after thefirst differential signal S_(diff1) is confirmed by the channel I.

It is appreciated that the shape and size of the drive electrode and thesense electrode in FIGS. 1 to 4 are only intended to illustrate, but notto limit the present disclosure. Preferably, the electrode set iscompletely covered when totally facing one of a plurality of fingers101. In addition, although FIGS. 1 to 4 show that the first electrodeset and the second electrode set are arranged respectively opposite toone finger and its adjacent space between two fingers (i.e. distanced bya half finger pitch), the present disclosure is not limited thereto. Forexample, d1 shown in FIG. 4 is selected to be arranged as (1+½) fingerpitch or longer. However, in order to reduce the size, preferably thefirst and second electrode sets are arranged as FIGS. 1 to 4.

It is appreciated that although the gear position detection device 3 ofthe present disclosure is illustrated by an example of being applied toa wrist watch 9, the present disclosure is not limited thereto. The gearposition detection device and the operating method shown in FIGS. 1 to 7are applicable to other devices having at least one gear, and theimplementation thereof is identical to the above embodiment only thesize and arrangement of the drive electrode and the sense electrode haveto be changed corresponding to the finger size and finger pitch. One ofordinary skill in the art would understand its implementation accordingto the above descriptions.

In addition, in an application without the size limitation, the driveelectrode and the sense electrode of the gear position detection device3 are arranged at two sides of the gear 10, e.g., including twosubstrates respectively used to dispose the drive electrode and thesense electrode.

As mentioned above, the conventional optical gear position detectiondevice has complicated manufacturing process and higher consuming power.Therefore, the present disclosure further provides a capacitive gearposition detection device (as shown in FIGS. 1 to 4) and an operatingmethod thereof (as shown in FIG. 7) that count a number of fingers bycounting a number of high levels of detected signals outputted by thecapacitive sensor. Furthermore, the gear position detection deviceincludes an index position to confirm a correct rotation angle to havethe effect of confirming the correctness of gear position.

Although the disclosure has been explained in relation to its preferredembodiment, it is not used to limit the disclosure. It is to beunderstood that many other possible modifications and variations can bemade by those skilled in the art without departing from the spirit andscope of the disclosure as hereinafter claimed.

What is claimed is:
 1. A wrist watch, comprising: a substrate; a gearcomprising a plurality of fingers and rotatable with respect to thesubstrate; a first drive electrode and a second drive electrode formedon the substrate; and a first sense electrode and a second senseelectrode formed on the substrate, wherein the first sense electrode isarranged adjacent to the first drive electrode, and the second senseelectrode is arranged adjacent to the second drive electrode, whereinthe first drive electrode and the first sense electrode form a firstelectrode set, the second drive electrode and the second sense electrodeform a second electrode set, and the first electrode set and the secondelectrode set are arranged in an arrangement that when one of the firstand second electrode sets are rotated to totally face one of theplurality of fingers, the other one of the first and second electrodesets is between two fingers of the plurality of fingers.
 2. The wristwatch as claimed in claim 1, wherein the substrate is a printed circuitboard of a flexible circuit board.
 3. The wrist watch as claimed inclaim 1, wherein the substrate is arranged at single side of the gear.4. The wrist watch as claimed in claim 1, wherein the gear further hasan index through hole which is aligned with, along a radial direction ofthe gear, one of the plurality of fingers or aligned with a spacebetween two fingers of the plurality of fingers.
 5. The wrist watch asclaimed in claim 4, further comprising an index drive electrode and anindex sense electrode adjacent to each other along the radial directionof the gear, wherein the index drive electrode and the index senseelectrode are aligned with, along the radial direction of the gear, thefirst electrode set or the second electrode set.
 6. The wrist watch asclaimed in claim 5, further comprising a drive chip configured to drivethe first and second drive electrodes, receive a first detected signalfrom the first sense electrode and receive a second detected signal fromthe second sense electrode, wherein the control chip is furtherconfigured to calculate a first differential signal between the firstdetected signal and the second detected signal, and count a number ofhigh levels of the first differential signal.
 7. The wrist watch asclaimed in claim 6, further comprising: a third drive electrode and afourth drive electrode formed on the substrate; and a third senseelectrode and the fourth sense electrode formed on the substrate,wherein the third sense electrode is arranged adjacent to the thirddrive electrode and the fourth sense electrode is arranged adjacent tothe fourth drive electrode, wherein the third drive electrode and thethird sense electrode form a third electrode set, the fourth driveelectrode and the fourth sense electrode form a fourth electrode set,and the third and fourth electrode sets are arranged in an arrangementthat when one of the first and second electrode sets are rotated tototally face one of the plurality of fingers, the third and fourthelectrode sets do not totally face one of the plurality of fingers andare not between a space between two fingers of the plurality of fingers.8. The wrist watch as claimed in claim 7, wherein the control chip isfurther configured to drive the third and fourth drive electrodes,receive a third detected signal from the third sense electrode andreceive a fourth detected signal from the fourth sense electrode,calculate a second differential signal between the third detected signaland the fourth detected signal, and identify a rotation direction of thegear according to phases of the first differential signal and the seconddifferential signal.
 9. The wrist watch as claimed in claim 6, whereinthe drive chip is configured to drive the first and second driveelectrodes with a square wave.
 10. A detection circuit, configured todetect rotation of a gear having a plurality of fingers, the detectioncircuit comprising: a substrate configured to be arranged opposite tothe gear; multiple drive lines and multiple sense lines formed on thesubstrate; a first drive electrode and a second drive electrode formedon the substrate and respectively connected to one of the multiple drivelines; and a first sense electrode and a second sense electrode formedon the substrate and respectively connected to one of the multiple senselines, wherein the first sense electrode is arranged adjacent to thefirst drive electrode, and the second sense electrode is arrangedadjacent to the second drive electrode, and a control chip connected tothe first and second drive electrodes via the one of the multiple drivelines, and connected to the first and second sense electrodes via theone of the multiple sense lines.
 11. The detection circuit as claimed inclaim 10, wherein the substrate is a printed circuit board of a flexiblecircuit board.
 12. The detection circuit as claimed in claim 10, whereinthe first drive electrode and the first sense electrode form a firstelectrode set, the second drive electrode and the second sense electrodeform a second electrode set, and the detection circuit further comprisesan index drive electrode and an index sense electrode which are alignedwith the first electrode set or the second electrode set.
 13. Thedetection circuit as claimed in claim 12, wherein the control chip isconnected to the index drive electrode via another one of the multipledrive lines, and connected to the index sense electrode via another oneof the multiple sense lines.
 14. The detection circuit as claimed inclaim 10, further comprising: a third drive electrode and a fourth driveelectrode formed on the substrate and connected to another one of themultiple drive lines; and a third sense electrode and the fourth senseelectrode formed on the substrate and connected to another one of themultiple sense lines, wherein the third sense electrode is arrangedadjacent to the third drive electrode, and the fourth sense electrode isarranged adjacent to the fourth drive electrode.
 15. The detectioncircuit as claimed in claim 14, wherein the control chip is connected tothe third and fourth drive electrodes via the another one of themultiple drive lines, and connected to the third and fourth senseelectrodes via the another one of the multiple sense lines.
 16. Thedetection circuit as claimed in claim 10, wherein the first driveelectrode and the first sense electrode form a first electrode set, thesecond drive electrode and the second sense electrode form a secondelectrode set, and the first electrode set and the second electrode setare arranged adjacent to each other along a tangential direction of thegear.
 17. The detection circuit as claimed in claim 16, wherein thefirst sense electrode is arranged adjacent to the first drive electrodealong a radial direction of the gear, and the second sense electrode isarranged adjacent to the second drive electrode along another radialdirection of the gear.
 18. The detection circuit as claimed in claim 10,wherein the detection circuit is adapted to a watch.